JP2005144284A - Ceramic honeycomb structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic honeycomb structure constituted so that a faulty part generated on the outer wall of this structure can be repaired surely without deteriorating the mechanical strength and thermal impact resistance of this structure and that a liquid leaks to the outer wall at a catalyzing step can be eliminated. <P>SOLUTION: This ceramic honeycomb structure has many flow passages divided by many partition walls and the outer wall for dividing the flow passages from the outside. At least one or more faulty parts being openings are filled/plugged with a ceramic material, which are generated on the surface of the outer wall and each of which has ≥0.1 mm width and is communicated with the flow passages. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a ceramic honeycomb structure in which a crack penetrating an outer wall generated in a manufacturing process and a hole-like defect including a crack are repaired.

In recent years, in connection with air pollution prevention, strengthening of automobile exhaust gas regulations has been studied.
Currently, a catalytic converter using as a carrier a ceramic honeycomb structure having a large number of through-holes (cells) surrounded by partition walls formed integrally by extrusion molding is used for exhaust gas purification for automobiles. However, as a method of further improving the purification efficiency, studies have been made on improving the so-called warm-up characteristics, which increases the catalyst activity from the beginning of the operation by reducing the heat capacity of the ceramic honeycomb structure and facilitating warming. ing.

In order to reduce the heat capacity of such a honeycomb structure, it is necessary to make it lighter (lower bulk density) without changing the geometric surface area of the honeycomb structure. Measures are taken such as reducing the thickness of the partition walls, that is, the thickness of the honeycomb ribs or increasing the porosity. For example, the thinning of the honeycomb partition walls is usually accompanied by a decrease in the mechanical strength of the honeycomb structure, which is extremely difficult in terms of production technology, and the honeycomb structure ( Since the outer wall of the honeycomb formed body) is different from the partition wall in the amount of the clay, it is inevitably unbalanced. If the outer wall is made thicker, cell deformation defects will occur, and if it is made thinner, the outer wall will be cracked. The molding of the outer wall portion of the structure is the point of manufacturing technology.

Therefore, in the case of such a honeycomb structure, cracks penetrating the outer wall at a certain ratio in the drying and firing processes, and hole-like defects including cracks, such as defects penetrating various outer walls shown in FIG. , Horizontal cut 2 and vertical cut 3) will occur.

As described above, the cracks penetrating the outer wall generated in the manufacturing process of the ceramic honeycomb structure, and the hole-like defects including the cracks cause defects in the catalytic process. In the catalyzing step, an aqueous slurry containing a material mixed with γ-alumina for increasing the specific surface area, ceria which is an oxygen storage material, zirconia which enhances heat resistance, etc. is sealed at the outer periphery of the ceramic honeycomb structure. Is applied to the honeycomb flow path. At this time, if a hole penetrating the outer wall is opened, when positive pressure is applied to the aqueous solution, leakage to the honeycomb outer peripheral portion occurs, the leaked portion is wasted, and it becomes a sealing failure in the next processing, On the other hand, when the end face of the honeycomb structure has a negative pressure, a problem that the slurry does not adhere occurs.

In addition, the honeycomb catalyst obtained in the catalyzing step is used in an airtight metal container. However, since the thermal expansion coefficient of the metal container is larger than the thermal expansion coefficient of the honeycomb catalyst, the metal container is heated when heated during use. In order not to loosen even if expanded more than the honeycomb catalyst, mechanical pressure is applied in advance so that the catalyst is put into a metal container through a ceramic mat having a cushioning property. Here, if the catalyst is fixed to the outer wall of the ceramic honeycomb catalyst, the mechanical pressure at that portion increases, and the honeycomb catalyst may be destroyed in some cases.

In order to solve the above problems, for example, a honeycomb structure whose outer peripheral portion is coated with a thick reinforcing material (see, for example, Patent Document 1), a honeycomb structure without an outer wall cut out from a molded and fired honeycomb structure For applying an outer wall to the outer periphery of the honeycomb structure (for example, see Patent Document 2), applying a glaze to the outer peripheral wall of the honeycomb structure (for example, see Patent Document 3), What is filled (for example, see Patent Document 4), what reduces the porosity of the outer peripheral portion including the outer wall of the honeycomb structure (for example, see Patent Document 5), and ceramic material on the outer periphery of the honeycomb structure having poor dimensional accuracy. A technology for obtaining a material with good dimensional accuracy (see, for example, Patent Document 6) and a technique in which an incomplete cell on the outermost periphery is selectively closed with a ceramic material (for example, see Patent Document 7) To have.
Japanese Patent Publication No. 51-44713 Japanese Utility Model Publication No. 53-34373 Japanese Utility Model Publication No. 53-133860 JP 56-129042 A JP-A-56-129043 No. 7-183 JP 7-246341 A

However, Patent Documents 1 to 7 have the following problems. Patent Document 1 can certainly repair defects on the outer wall, but the thermal expansion coefficient of the reinforcing material is larger than that of the cordierite honeycomb structure, and when the material is coated on the outer wall, the thermal shock resistance is only reduced. In addition, since the reinforcing material is coated, the heat capacity is increased, the temperature rise of the catalyst is delayed, and the purification performance at the cold start is deteriorated.

Patent Document 2 is a device for imparting an outer wall to a honeycomb structure without an outer wall cut out from a molded and fired honeycomb structure, and is a large through-hole penetrating the outer wall (for example, a through-hole having a diameter of 0.1 mm or more). ) Is not a technology to block.

Patent Document 3 applies glaze to the outer peripheral wall, but cannot fill defects such as large holes having a diameter of 0.1 mm or more and relatively deep cracks. Further, since the thermal expansion coefficient of the glaze is larger than that of the honeycomb structure, the thermal shock resistance is lowered.

Although the patent document 4 can certainly repair the defect of the outer wall, since the exhaust gas does not flow through filling the cell in the outer peripheral portion, it is dead for the exhaust gas purification that is the purpose of the catalyst. It becomes a zone. Recently, since the entire volume is used, only the side surfaces of the honeycomb structure are mechanically held and used, and in this technique, the portion where the flow path is filled is completely wasted. Incidentally, in the case of a catalyst having a diameter of 100 mm, if a dead zone having a width of 3 mm is provided, a waste of about 10% or more is generated.

In Patent Document 5, the pores of a normal ceramic honeycomb structure are mainly small holes of 50 μm or less, and this technique is a technique for filling these holes. For example, a large hole having a diameter of 0.1 mm or more, Defects such as deep fissures could not be filled.

Patent Document 6 is a technique for obtaining a ceramic material with a good dimensional accuracy by supplementing the outer periphery of a honeycomb structure with a poor dimensional accuracy. However, in some cases, the ceramic material is not supplemented. In part, since a coating layer of 0.5 mm or more exists, purification performance deterioration at cold start is inevitable.

In Patent Document 7, an incomplete cell on the outermost periphery is selectively closed with a ceramic material, but cracks penetrating the outer wall and hole-like defects including cracks (see FIG. 1) are not considered at all. For this reason, if the defect happens to be in the incomplete cell portion, the defect is blocked, but if the defect is in the complete cell portion, it cannot be closed.

The present invention has been made in view of the above-described problems of the prior art, and the object of the present invention is to reliably repair a defective portion generated on the outer wall without reducing mechanical strength and thermal shock resistance. Another object of the present invention is to provide a ceramic honeycomb structure that can solve the problem of liquid leakage to the outer wall in the catalytic step.

That is, according to the present invention, there is provided a ceramic honeycomb structure having a large number of flow paths partitioned by a large number of partition walls and an outer wall partitioning the flow path and the outside, and the openings generated on the surface of the outer wall. There is provided a ceramic honeycomb structure having a width of 0.1 mm or more and at least one defect portion in which the opening portion communicates with the flow path and filled with a ceramic material.

At this time, in the present invention, the thickness of the partition wall is preferably 0.115 mm or less, and it is preferable that the ceramic material is packed not only in the opening but also in a flow path communicating with the opening.

In the present invention, the ceramic material is preferably composed mainly of the same material as the ceramic honeycomb structure. When the ceramic honeycomb structure is a molded body formed using a water-soluble binder, the ceramic material is preferably composed of a raw material kneaded with oil.
When the ceramic honeycomb structure is a fired body, the ceramic material (cement material (1)) is preferably composed mainly of cordierite powder and colloidal silica.

Furthermore, in the present invention, when the ceramic honeycomb structure is a fired body, the ceramic material (cement material (2)) is preferably a catalyst slurry material mainly composed of γ-alumina.

In the present invention, the thermal expansion coefficient of the portion of the honeycomb structure packed with the ceramic material is preferably less than 3.0 × 10 ⁻⁶ / ° C.

The ceramic honeycomb structure of the present invention can surely repair a defective portion generated on the outer wall without deteriorating mechanical strength and thermal shock resistance, and solves a problem of liquid leakage to the outer wall in the catalyzing process. be able to.

A ceramic honeycomb structure according to the present invention is a ceramic honeycomb structure having a large number of flow paths partitioned by a large number of partition walls, and an outer wall that partitions the flow path and the outside, and an opening generated on the surface of the outer wall The ceramic material is filled and plugged into at least one defect portion having a width of 0.1 mm or more and an opening portion communicating with the flow path.

As a result, the ceramic honeycomb structure of the present invention has the mechanical strength and heat resistance of the defective portion generated in the outer wall such as a large hole having a diameter of 0.1 mm or more and a relatively deep crack, which has been difficult with the prior art. The repair can be surely performed without reducing the impact property, and the liquid leakage problem to the outer wall in the catalyzing process can be eliminated, so that the yield and performance of the ceramic honeycomb catalyst can be improved.

First, the outer wall defects and problems of the ceramic honeycomb structure will be described in detail.
As shown in FIG. 1, various penetrating defects are generated on the outer wall of the ceramic honeycomb structure. No. 1 is called “Sasakure” and occurs when the material supply for forming the outer wall is small at the time of molding. Smaller ones become holes. Depending on the state, it may be a tear, and a crack may occur from the end. No. 2 is called “horizontal cut” and occurs due to rapid partial drying of the outer wall or rapid contraction of the outer periphery during firing. No. 3 is called “vertical cut” and is manifested in the drying / firing process due to insufficient pressure bonding of the material at the time of molding, or occurs due to rapid drying / firing shrinkage of the outer wall.

Since a part of the raw material forming the outer wall is also supplied from the slit for forming the partition wall of the die, the material with a small partition wall thickness tends to decrease the supply of the raw material to the outer wall. If the thickness is 115 mm or less, the outer wall is likely to be crumpled. In addition, when the outer wall thickness is thinner than the case where the outer wall thickness is thinner, the width of the slit and the length of the warp are more likely to be affected by changes in the external state and insufficient crimping, and the appearance of the partition wall is greater than 0.115 mm. Defects are likely to occur. Table 1 shows the defect occurrence rate during molding in one month.

When the honeycomb structure having these defects is flowed in the catalytic step, various problems occur. In the catalyzing step, the honeycomb structure end face is immersed in the slurry for several mm to seal the outer wall of the honeycomb, and when negative pressure is applied to the other end face, the slurry rises in the honeycomb flow path. When the slurry level reaches the predetermined position, if the pressure is released, the level returns to the original level, and then the excess slurry in the taken-out honeycomb channel is blown off.

At this time, if there is a hole in the outer wall, the pressure of the flow path is not carried because the slurry liquid level does not rise because air enters through the hole and does not become negative pressure. In addition, if a positive pressure is applied to the liquid in the above state, the liquid level rises in the honeycomb flow path, and the rest is processed in the same manner. However, if there is a hole in the outer wall, the slurry leaks from the hole and seals. The material is soiled to deteriorate the sealing performance, and the slurry hangs on the outer wall.

The noble metal to be used as a catalyst may be separately supported after the slurry is supported, or a slurry material in which the noble metal is previously supported may be used. However, it takes a long time to support the noble metal in the slurry. In this case, the entire honeycomb structure is generally immersed in the noble metal solution. Therefore, in any case, the noble metal is supported on the slurry dripping on the outer wall and is wasted.

As for the size of the defect, the normal ceramic honeycomb structure has pores, and most of them are 50 μm or less as measured by mercury porosimetry. In the catalyst process, if a through hole having a diameter of 0.1 mm or more, which is twice the diameter, is present on the outer wall, troubles will occur when the slurry is introduced into the flow path under negative pressure. Further, the size of the through hole when the slurry starts to leak from the outer wall is greatly influenced by the viscosity of the slurry, but is empirically from about 0.5 mm or more. In the case of a through hole of about 0.3 mm, there is a case where it leaks, but generally it is very small and is an acceptable level. As the partition wall thickness is 0.115 mm or thinner, the viscosity of the slurry is lowered so as not to cause clogging as the flow path density becomes 62, 93, 140 / cm ^2. Defects have become more apparent.

In consideration of the above problems, the ceramic honeycomb structure of the present invention has solved the problem of liquid leakage to the outer wall in the catalytic step even when the partition wall thickness is 0.115 mm or less.

At this time, most of the ceramic honeycomb structures having a partition wall thickness of 0.115 mm or less have few defects on the outer wall, so that the ceramic material for repairing the outer wall is put in a putty shape and applied. It is preferable to fill in the defective part.

In this case, it is preferable that the ceramic material is packed not only in the opening but also in a flow path communicating with the opening. This is because if the flow path is blocked, the slurry is not carried but the exhaust gas does not flow, and even if the flow path is closed by repairing several places, the purification performance and pressure loss are not affected. Further, in the case of a large-sized defect, the repaired portion is less likely to be peeled off if the repair material is bonded only by the outer wall and is closed to the flow path.

In the present invention, the thermal expansion coefficient of the honeycomb structure in which the ceramic material is packed is 3.0 × 10 ^{− in} order to prevent a decrease in mechanical strength and thermal shock resistance during actual use of the honeycomb structure. It is preferably less than ⁶ / ° C.

When repairing the ceramic honeycomb structure of the present invention before firing, it is preferable that the ceramic material (repair material) is made of the same material as the honeycomb structure in a putty shape.
Here, the same material as the honeycomb structure means a ceramic raw material excluding a liquid for forming and a binder. The material of the honeycomb structure before firing used at this time is not particularly limited, but when a cordierite raw material that becomes cordierite when the honeycomb structure is fired is used, the repair material is also the same cordierite raw material. Can be suitably used.
Further, when water and a water-soluble binder are used when forming the honeycomb structure, it is preferable to knead into a putty using water-insoluble oil or the like so that the honeycomb structure formed body is not deteriorated by the repair material. . Although the oil used at this time is not specifically limited, For example, kerosene can be used suitably. If the liquid and the binder are not water and a water-soluble material, the oil is not limited to oil. When a water-insoluble liquid and a binder are used, water can be used as the repair material.

In the ceramic honeycomb structure of the present invention, when repair is performed after firing the honeycomb structure, the defect of the outer wall is repaired by using a cement material (cement material (1) or cement material (1) as a ceramic material (repair material)). 2)) is preferably performed. The cement material may have a porosity and a water absorption rate equivalent to or lower than those of the honeycomb structure body, and may have water repellency. The cement material is desired to have small shrinkage due to drying, and it is necessary to prevent cracks penetrating by drying.

The cement material (1) preferably has the same thermal expansion coefficient as that of the honeycomb structure, and more preferably, the aggregate of the honeycomb structure body material is used for the aggregate to bring the thermal expansion coefficient closer.
Here, the granule of the honeycomb structure body material is usually cordierite powder, and a cement material (1) can be obtained by using a colloidal oxide as an inorganic binder in the cordierite powder. it can. In the cement material (1), the ratio of the cordierite powder and the colloidal oxide (in terms of solid content) is 100: 2 to 100: 50 by weight ratio. This is preferable in order to maintain the adhesiveness and the thermal characteristics of the honeycomb structure after repair. The cordierite powder is generally preferably a calcined powder having an average particle size of 50 μm or less, and is composed of a blend of a fine average particle size and a relatively coarse average particle size. For example, a mixture having a two-stage particle size distribution, for example, an average particle size of 15 μm or less and an average particle size of 30 μm or more can be used as appropriate. The colloidal oxide is not particularly limited, but for example, colloidal silica can be suitably used.

The cement material (2) is a catalyst slurry material mainly composed of γ-alumina used in the catalyzing step, and may be used as a repair material by adjusting the viscosity of the slurry in the catalyzing step.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.
(Examples 1 to 3, Comparative Examples 1 and 2)
The following evaluation was performed to select repair materials. When fired, it becomes cordierite, and the molded product of the honeycomb structure having a rib thickness of 0.09 mm, the number of flow paths of 62 / cm ² , a diameter of 106 mm × a height of 114 mm, and a thermal expansion coefficient of 0.5 × 10 ⁻⁶ / ° C. Each item was prepared.
Among the molded products, those with defects of cracks or vertical cuts were selected, repaired with the “before firing” ceramic material (repair material) shown in Table 2, and the repaired part was observed after firing (implementation) Example 1 and Comparative Example 1). In addition, among the molded products, those with defects such as cracks or vertical cuts are selected and fired, repaired with a “fired” ceramic material (repair material) shown in Table 2, and after heat treatment, the repaired part is observed. (Examples 2-3 and Comparative Example 2). The measurement of the thermal expansion coefficient was performed by cutting the sample into 3.5 × 3.5 × 50 Lmm so as to include the portion where the vertical cut portion was repaired. The heat treatment was performed at 900 ° C. which could be used in an automobile, and was performed in an electric furnace for 10 hours.

From the results of Table 2, in Examples 1 to 3, since the thermal expansion coefficient of the ceramic material (repair material) approximated the thermal expansion coefficient of the honeycomb structure, it was possible to perform good repair without any abnormality. On the other hand, in Comparative Examples 1 and 2, the thermal expansion coefficient of the ceramic material (repair material) of alumina (Comparative Example 1) or zirconia silicate (Comparative Example 2) is larger than the thermal expansion coefficient of the honeycomb structure. There has occurred.

(Examples 4 and 5, Comparative Examples 3 to 5)
Forty ceramic honeycomb structures before fired, which have the sacra crab 1 (see FIG. 1), were prepared. Sasacle is a lip-shaped tear, has a maximum opening width of about 0.3 mm to 4 mm, a length of 4 to 10 mm, and a crack with a maximum of 5 mm at its end, extends in a direction perpendicular to the flow path, and has a length of 30 mm in the full length direction. 15 to 21 pieces are arranged in this part. The honeycomb structure material used was a raw material that became cordierite when fired, and 10 of these were kneaded in a putty shape with the same material so as to be flush with the outer wall and repaired. Thereafter, it was fired together with 30 non-repaired sacres and 10 non-repaired ones having no appearance defects, such as a cordierite honeycomb having a rib thickness of 0.065 mm, a number of channels of 140 / cm ² , a diameter of 106 mm and a height of 114 mm A structure was obtained. What was repaired was designated as Example 4, those not repaired as Comparative Example 3, and those without defects as Comparative Example 4.

In addition, 10 parts with baked salami without repair are mixed with 20% colloidal silica and 80% cordierite fine particles by weight, and a repair material kneaded into a putty shape is applied to the cradle part to be flush with the outer wall. The product was repaired and dried to obtain Example 5. Further, a mixture of 20% colloidal silica and zirconium silicate powder in a weight ratio of 80% in the form of a slurry was uniformly applied to the outer periphery of the honeycomb structure at a thickness of about 1 mm and dried to obtain Comparative Example 5.

For Examples 4 and 5 and Comparative Example 5, the flow path was observed through the end face. As a result, 10 to 12 flow paths adjacent to the outer wall of the salamander portion were blocked by the repair material. A thin cylindrical synthetic resin sheet was sealed and attached to the side surface close to the end face of these honeycomb structures, air was sent at 9 m ³ / min, and the repaired part was observed. As a result, air was leaked in Comparative Example 3 which was not repaired. However, since Examples 4 and 5 and Comparative Example 5 were free of air leak, the effectiveness of repair was confirmed.

Next, various performance tests shown below were conducted for Examples 4 and 5 and Comparative Examples 3 to 5, and the results are shown in Table 3.

For the pressure loss, a ceramic mat was wound around the outer periphery of the honeycomb structure, put in a cylindrical case, connected with a cone, and air was flown at room temperature, and the difference in pressure before and after the honeycomb was measured. As a result, all samples in Examples 4 and 5 and Comparative Examples 3 to 5 have the same value, and there is no effect even if the repair is performed and 10 to 12 flow paths are blocked by the repair material. confirmed.

Next, in order to confirm the carrier performance, a mechanical strength test and a thermal shock test were performed as follows.
(1) Mechanical strength test The mechanical strength test is also called an isostatic test, and an aluminum plate having a diameter of about 106 mm and a thickness of about 20 mm is placed on the upper and lower end surfaces of the honeycomb structure with a urethane sheet having a thickness of about 0.5 mm. Furthermore, the side was wrapped in a urethane tube with a thickness of about 0.5 mm and sealed in a pressure vessel filled with water. The water pressure was gradually increased, and when the pressure reached 1 MPa, it was removed from the vessel and the appearance was observed (load resistance test). ). Thereafter, the honeycomb structure was sealed again and placed in a pressure vessel, the pressure of water was increased, and the pressure when a breaking noise was made was recorded (destructive test). The test results are shown in Table 3 as average values of five samples.
(2) Thermal shock resistance test The thermal shock resistance test was carried out by placing a honeycomb structure at room temperature in an electric furnace maintained at 700 ° C + room temperature and using the method specified in the automotive standard JASO-M-505-87. The test was conducted. If there are no cracks or other abnormalities and metal sound is detected by hammering test, it is accepted. If crack is generated or muddy sound is detected by hammering test, it is rejected. It was. The test results are shown in Table 3 as an average value of four samples.

In the mechanical strength test, Examples 4 and 5 and Comparative Example 4 were in exactly the same state as before the test, but those that were not repaired (Comparative Example 3) opened with a 3-4 mm width of the brush. In addition, the outer wall of the adjacent portion was peeled off, and one defective portion 4 (hatched portion in FIG. 2) of about 5 × 4 to 10 × 8 mm in which 3 to 4 pieces were collected was generated. In addition, those that were not repaired (Comparative Example 3) were destroyed at a low value at the Sasakuri location, while those that were repaired (Examples 4 and 5 and Comparative Examples 4 and 5) were not destroyed at the repaired location. It was confirmed that the repair was rather improved in terms of mechanical strength.

In the thermal shock resistance test, the acceptable maximum temperature was a difference of 850 ° C. for all four types of samples (Examples 4 and 5 and Comparative Examples 3 and 4), and cracks were formed in the non-sacrifice portion. It has been confirmed that repairing the sacra crab does not affect the thermal shock resistance. On the other hand, in Comparative Example 5, a significant decrease was confirmed due to the effect of the repair material applied to the outer periphery. This is considered to be because zirconium silicate having a large thermal expansion coefficient of 10 × 10 ⁻⁶ / ° C. was applied to the entire outer surface.

(Examples 6 and 7, Comparative Examples 6 to 8)
40 pre-fired ceramic honeycomb structures having 5 vertical cuts 3 (see FIG. 1) within 180 ° were prepared. In the vertical cut, the outer wall has a width of about 0.4 mm and extends over the entire length, and the depth (in the radial direction) is cut to the outer wall and the next two walls. As in Example 4, ten pieces kneaded with oil were applied and repaired. Then, it fired with the thing which is not repaired, and obtained the cordierite honeycomb structure of rib thickness 0.09mm, the number of flow paths 62 pieces / cm < ² >, diameter (phi) 106mm x height 114mm.

What was repaired was designated as Example 6, those not repaired as Comparative Example 6, and those without defects as Comparative Example 7.
Then, 10 pieces fired without repairing were repaired so that the outer wall was flush with a repair material prepared by mixing 80% by weight of colloidal silica with 80% colloidal silica and kneading into a putty. 7 was obtained. Further, 10 samples fired without repair were coated with zirconium silicate on the outer wall in the same manner as in Comparative Example 5 to obtain Comparative Example 8.

Next, various performance tests shown below were carried out for Examples 6 and 7 and Comparative Examples 6 to 8, respectively, and the results are shown in Table 3. In Examples 6 and 7, the flow path was observed from the end face, and as a result, only one flow path adjacent to the outer wall was blocked with the repair material at five locations. These honeycomb structures were dropped out as in Example 1 and tested for air leakage, but there was no abnormality. Moreover, the pressure loss was the same as in Example 1, and there was no difference among the five persons (Examples 6 and 7 and Comparative Examples 6 to 8).

In the load resistance test in the mechanical strength test, the repaired product (Examples 6, 7 and Comparative Examples 7 and 8) is excellent, and in the destructive test, 5 persons (Examples 6 and 7 and Comparative Examples 6 to 8) are used. There was no difference. The bending of the outer wall in the load-bearing test (Comparative Example 6) is not normally rejected, but if it occurs during canning, the outer wall of the bent portion is scattered due to vibration during use, etc., but it is exhausted although it is 1 cell wide Since the gas is in direct contact with the ceramic mat for mechanical support of the honeycomb structure, it is rather undesirable.

In the thermal shock test, one of the repaired products (Examples 6 and 7) cracked at one of the repair points (the remaining seven had cracks at the unrepaired points), but the non-repaired product (comparison) In Example 6), one of the four pieces had cracks in the vertical cut portion. From this result, cracks may occur in the vertical cut portion, but considering that there is no difference in the destruction temperature, it is considered that the repair does not adversely affect the destruction temperature.

The ceramic honeycomb structure of the present invention can be suitably used for a filter for collecting particulates in exhaust gas from an internal combustion engine, a boiler or the like.

It is a perspective view which shows typically each example of the defect which generate | occur | produces in the outer wall of a ceramic honeycomb structure. It is a fragmentary perspective view which shows typically the defect | deletion part which the outer wall of the adjacent part opened with the width | variety of 3-4 mm of the sacre in Comparative Example 3 generate | occur | produced.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sasakure, 2 ... Slice, 3 ... Slice, 4 ... Defect part, 10 ... Ceramic honeycomb structure.

Claims (8)

A ceramic honeycomb structure having a large number of flow paths partitioned by a large number of partition walls and an outer wall that partitions the flow paths and the outside,
A ceramic honeycomb structure in which a width of an opening generated on the outer wall surface is 0.1 mm or more, and at least one defect portion in which the opening communicates with the flow path is filled with a ceramic material and blocked. body. The ceramic honeycomb structure according to claim 1, wherein the partition wall has a thickness of 0.115 mm or less. The ceramic honeycomb structure according to claim 1 or 2, wherein the ceramic material is packed not only in the opening but also in a flow path communicating with the opening. The ceramic honeycomb structure according to any one of claims 1 to 3, wherein the ceramic material is mainly composed of the same material as the ceramic honeycomb structure. 5. The ceramic honeycomb structure according to claim 4, wherein when the ceramic honeycomb structure is a molded body formed using a water-soluble binder, the ceramic material is composed of a raw material kneaded with oil. body. The ceramic honeycomb structure according to claim 4, wherein when the ceramic honeycomb structure is a fired body, the ceramic material is mainly composed of cordierite powder and colloidal silica. The ceramic honeycomb structure according to any one of claims 1 to 3, wherein when the ceramic honeycomb structure is a fired body, the ceramic material is a catalyst slurry material mainly composed of γ-alumina. The ceramic honeycomb structure according to any one of claims 1 to 7, wherein a thermal expansion coefficient of a portion of the honeycomb structure packed with the ceramic material is less than 3.0 x ^10-6 / ° C.

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